The present invention relates to a listening clamp for an acoustical vibration analysis tool, and an acoustical vibration analysis tool using such a listening clamp. These objects are used in particular during maintenance operations or after-sales service of automotive vehicles.
An acoustical vibration analysis tool comprises, in a known manner, a headset suitable for noisy environments, a microphone, four clamps for the detection of noise of a structural nature and a selector for immediate identification of the clamp nearest to the acoustical vibration phenomenon to be detected.
A known type of listening clamp comprises two pivotally connected arms, each comprising a jaw and a handle arranged on both sides of the pivot point. This kind of clamp comprises a return spring defining a closed rest position of the jaws. The jaws are rigid metallic bodies that directly grip on the element to be measured, such as the usual jaws of battery charge clamps. The sensor comprises a single axis accelerometer glued on one jaw at a distance from the contact zone. With such a clamp, only the vibrations produced in a direction perpendicular to the positioning of the accelerometer in the clamp are transformed into electric signals and can be heard by the operator. In addition, significant loudness and level variations are induced by the positioning of the clamp on the structure to be analyzed. The sensing quality is mediocre and makes diagnosis relatively difficult. In addition, with this type of clamp there is a risk of short circuits, which can be particularly inconvenient, in particular when the clamps are used with hybrid vehicles. Furthermore, the different types of applications of such a clamp in a vehicle, specifically on a powertrain group or on ground connections, require the use of several sets of listening clamps of different dimensions (in general the listening clamps of the same tool are of three different sizes), and on the same element of the structure, listening is chosen according to the selected clamp, which consequently creates difficulties and/or interpretation errors.